Dark energy: the decade ahead

Ten years after astrophysicists discovered that the expansion of the universe is accelerating,
further measurements have given us few clues into the nature of the dark energy that drives it.
But, as Eric Linder and Saul Perlmutter describe, advances in observational techniques promise
to shed light on this revolutionary physics in the decade ahead

A decade ago, the universe was diagnosed with a severe
— possibly even terminal — case of "dark energy". Based
on observations of very distant supernovae, at the
beginning of 1998 two teams of astrophysicists announced
the astonishing conclusion that the cosmic
expansion is actually accelerating — and not slowing
under the influence of gravity as might be expected.
The implication was almost beyond belief: in order to
account for the acceleration, about 75% of the mass—
energy content of the universe had to be made up of
some weird, gravitationally repulsive substance that
nobody had ever seen before. This substance, which
would determine the fate of the universe, was dubbed
dark energy.

Like a person confronted with the diagnosis of a
life-threatening illness, the scientific community progressed
through five stages of reaction to the discovery
of dark energy: denial, anger, bargaining, depression
and acceptance. Thanks to a number of independent
observations, we are now well over the first stage.

For a start, measurements of the cosmic microwave
background — the bath of microwave radiation left over
from the Big Bang — made in 2000 by the Boomerang
and MAXIMA balloon experiments, and in 2003 by the
WMAP satellite, have provided independent support
for an accelerating universe. Further evidence has
come from the Sloan Digital Sky Survey, which in 2005
measured "ripples" in the distributions of galaxies that
were imprinted in acoustic oscillations of the primordial
plasma 360,000 years after the Big Bang when the
universe had cooled sufficiently to allow matter and
radiation to decouple. Astronomers have also shored
up their evidence for an accelerating universe by studying
gravitational lensing — the way light from distance
sources is bent by the gravitational fields of massive
intervening galaxy clusters. Finally, the original supernova
approach itself has been extended and strengthened
by including more objects, measured more
accurately and across a greater range of cosmic history,
with the help of both ground-based telescopes and the
Hubble Space Telescope (see "Supernovae as distance markers").

Together, these observations have led cosmologists
to a description of the universe called the concordance
model. In this picture, 75% of the cosmic mass energy
exists as a mysterious, gravitationally repulsive accelerating
component, while the remaining 25% has attractive
gravitational interactions. In fact, the majority of this
25% (about 5/6) is not even normal matter but rather
some additional unknown substance — called dark matter
— that gravitates normally yet does not couple to electromagnetic
radiation. In all, the concordance model
shows that we only understand a somewhat shameful
4% of the content of our universe.

Facing up to data

By the end of 2003 denying the cosmic acceleration was
no longer an option. By that time, however, frustration
or anger had begun to set in. Just as a patient might cry
"why me, why now?", so did physicists trying to understand
why the universe was accelerating at all, and in
particular why it was doing so now. This is because
while the supernova observations could not tell us precisely
what dark energy is, its effect on tearing the universe
apart is tantalizingly similar to what one would
expect if the universe is permeated by Einstein's long-abandoned
cosmological constant.

Just after Einstein had unveiled his general theory of
relativity in 1915 — which describes the dynamics of the
universe and the evolution of the matter and energy in
it — he introduced a constant into his equations to counteract
the attractive pull of normal matter. He did this
because he wanted his new theory to fit the then belief
that the universe was static. But when, in 1929, Edwin
Hubble showed that the universe was expanding,
Einstein was forced to take the cosmological constant
out again. Nevertheless, ever since then the possibility
of gravitationally repulsive energy has remained in
Einstein's theory.

Intriguingly, although a "cosmological constant" is
ultimately a source of intense frustration for physicists,
it is also predicted by the physics of the very small:
quantum mechanics. Quantum field theory predicts
that even empty space has an energy density due to the
spontaneous creation and annihilation of elementary
particles. Based on the particles that we know to exist,
however, the vacuum energy density according to quantum
mechanics should be an embarrassing 10120 times
larger than the value that is required to explain the
cosmic acceleration.

Adding to the conundrum of having such a natural
candidate for dark energy that is 120 orders of magnitude
too large, the cosmic acceleration also appears to
have begun only recently in cosmic history. Presumably
the cosmological constant could have overtaken the
gravitational influence of matter at any time during the
last 13.7 billion years during which the universe expanded
by a factor of 1028 or so. Yet it kicked in only
during the last factor of two expansion — a coincidence
with odds of just 2 in 1028! These absurdities seem
arranged purely to drive scientists crazy, or to an anthropic
explanation in which the laws of nature are
somehow linked to our presence.

Physicists countered the anger with bargaining: perhaps
we are not dealing with a true cosmological constant
but a varying quantum field that adjusts the
energy density of the vacuum as the universe expands.
This would also be reminiscent of inflation — a period
immediately after the Big Bang during which the universe
expanded by a factor of perhaps 1026 in just
10–33 s. Maybe the magnitude of the measured cosmological
constant is small because the universe is old,
and perhaps the reason why acceleration occurred so
close to the present time is because matter only came
to dominate over radiation and form dense structures
fairly recently.

Since 1998, theorists have investigated a wide variety
of such models, for example involving new quantum
fields such as "quintessence" and extensions of
general relativity (see "The mysterious vacuum"). Great progress has been
made in winnowing through the garden of models, but
a lush thicket remains. The difficulty in deciding among
the many proposals for dark energy — coupled with the
fact that most measurements we can perform to try and
understand its properties rely on the complicated astrophysics
of distant objects — has brought some of the
community to the stage of depression.

However, advances in the last few years show that
there may be light at the end of the tunnel. A combination
of next-generation experiments, theory and
computation should soon lead researchers to the stage
of acceptance, and hopefully beyond this to an understanding
and appreciation of the nature of our
accelerating universe.

Learning to walk

In the 10 years since the discovery of the cosmic acceleration,
researchers have learned the basics of how to
walk and talk. Much of this has involved determining
the "equation of state" for dark energy. Einstein showed
that in addition to mass, all forms of energy contribute
to gravity. In particular, general relativity predicts that
the strength of gravitational attraction is governed by a
particular combination of the energy density, ρ, and the
pressure, p, in the form: ρ + 3p. However, if the pressure
is negative (as it is when two objects are separated
by coiled springs, for example), this combination can
have a value less than zero, thus turning gravity from an
attractive to a repulsive force.

Physicists therefore often define the equation of state
in terms of the quantity w = p/ρ, where w has to be less
than –1/3 to cause cosmic acceleration. Einstein's cosmological
constant corresponds to w = –1, since a situation
in which the pressure is equal and opposite to
the energy density is the only way to achieve a unique
energy density that does not change in space and time,
as Einstein had thought. But in trying to understand
the nature and origin of dark energy, researchers have
moved beyond this simplest of equations of state and
investigated other values of w and in particular now
seek to understand the dark-energy properties as a
function of time, w(t).

Thanks to the data collected via ground- and space-based
observations over the last decade, we know that w
averaged over the last 7 billion years — from when the
universe was half its present size — is within 10% of
Einstein's cosmological constant, w = –1. The period of
acceleration appears to have started about 5 billion
years ago, before which dark energy was scarce enough
that gravity dominated and caused gradual slowing of
the expansion of the universe (i.e. cosmic deceleration).

Our understanding of how dark energy actually arose
and whether it varies with time is much more modest.
For example, all we can conclude so far is that w has not
varied by much more than a factor of two over the last
7 billion years. The challenge now is to turn our knowledge
of w into a precision measurement, with an uncertainty
of a couple of per cent, and to know how it
varies with time to a precision better than 10%. Then
we will have a much better guide to what new physics
has taken over our universe.

One way to achieve this is to collect more types of
data using direct and well-understood cosmological
probes. Simply obtaining more data of the sort we
already have is insufficient; we need to observe supernovae
and galaxies that lie deeper into space, and thus
further back in time. We also need to be able to separate
much more cleanly than we can at present the true
properties of the universe from imperfections in our
observations. For example, a supernova could appear
to us as dim either because it lies further away or because
its light has been scattered by dust in the galaxy
where it resides, and gravitational lensing can be mimicked
by the blurring of the telescope image due to the
Earth's atmosphere.

Because many of the properties of dark energy are
mixed up with other quantities, such as the density of
matter in the universe, it is also vital to use several different
observational techniques. Furthermore, since
dark energy has both direct effects on cosmic distances
and indirect effects on the growth of galaxies and clusters
of galaxies (since it is hard for clumps of mass to
grow if the space between them is being rapidly pulled
apart), complementary techniques can also help answer
the important question of what flavour of new physics
is required (see "Multiple approaches", below). This could be a new physical
ingredient such as a quantum field energy, which would
affect cosmic distances and galaxy growth in the same
way, or a new physical law that extends Einstein gravity,
which might affect distances and growth differently.

If we look at astronomers' track record of discovering
new physics, we can see why we need new observations
to resolve the issue. The 18th-century puzzle over
the motion of planets in the outer solar system was
solved by adding a new physical ingredient — the planet
Neptune, which was discovered in 1829. The 19th-century
puzzle over the motion of the inner planet
Mercury, on the other hand, led to an extension of
Newtonian gravity: general relativity. The 20th-century
puzzle over motions of stars within galaxies will
probably be solved by the discovery of a new ingredient
— dark-matter particles, although we have not found
them yet. For dark energy, which is currently the most
pressing problem in cosmology, the mystery of new
ingredient versus new law can only be decided through
carefully planned experiments.

Tuning in to the early universe

There are four main experimental techniques that will
allow us to shed light on the mystery of dark energy.
The first is to look for ripples in the distributions of
galaxies, which originated in acoustic oscillations of
baryonic (i.e. normal) matter when it was bound up
with the cosmic background radiation before matter
and radiation decoupled. Like leaves (the baryons)
floating in a pond (the background radiation), ripples
in the water are revealed in the pattern of leaves. Since
we can measure the wavelength of the ripples from the
pattern of temperature fluctuations in the cosmic
microwave background, we can compare them to observations
of the galaxy pattern across the sky to determine
the distances at which those galaxies lie.

Because only 1/6 of all matter is baryonic, while the
rest is in some dark form that gravitates but does not
couple to light (like stones in the pond that are unaffected
by the motion of the water), the baryonic oscillation
pattern is much more subtle than the temperature
fluctuations we see directly in the microwave background
using probes such as WMAP. However, in 2005
the Sloan Digital Sky Survey, which is based on data
taken by a 2.5 m telescope located in New Mexico looking
back 4 billion years, detected the faint baryon ripples.
Indeed, as stated earlier, the fact that the galaxy
patterns agreed with the concordance model supports
the discovery of the accelerating universe.

To improve the precision of the measurements we
now need to extend such galaxy surveys to much larger
volumes. Starting in 2009, the Baryon Oscillation Sky
Survey is scheduled to begin surveying one-quarter of
the sky out to a redshift z = 0.8, when the universe was
half its present age, as well as a slice of the universe at
about z = 2.5, when it was one-sixth its present age.
(The redshift is due to the stretching of light as the
universe expands and thus provides a distance measure:
z = (λobs – λ0)/λ0, where λobs is the wavelength of
light detected and λ0 the wavelength of the light when
it was emitted.) The Hobby–Eberly Telescope Dark
Energy Experiment (HETDEX), which is planned to
begin observations in 2010, will concentrate on this
latter slice in more detail.

The baryon-acoustic-oscillation method is mostly
sensitive to the matter density of the universe. This is
because such measurements require a comparison
between the observed size of acoustic ripples to the size
expected from the cosmic microwave background,
which originated in an era when the gravitational attraction
from matter should have dominated over the
gravitational repulsion from dark energy. When combined
with supernova observations, however, this plays
an important role in separating out the matter-density
from dark-energy properties.

A second technique for tackling dark energy is to
study the cosmic microwave background itself. The
temperatures and spatial extents of the hot and cold
spots in this sea of electromagnetic radiation provide
a superb probe of the primordial universe some 360,000
years after the Big Bang. Since the early universe
should be dominated by matter, with little dark energy,
the microwave background says relatively little directly
about the properties of dark energy. But, like the baryonic
acoustic oscillations, it plays an important role
in separating out the role of the matter density.

In addition to ongoing data from WMAP and groundbased
experiments, a new generation of cosmic-microwave-
background experiments such as Clover, EBEX,
PolarBear, QUIET and Spider — which will either be
built in the high Atacama Desert in Chile or flown on
balloons — are expected to collect data between 2008
and 2010. These observations — not to mention data
from the Planck satellite, which is due for launch in
2008 — will allow us to measure the polarization of the
cosmic microwave radiation and perhaps allow us to use
a form of weak gravitational lensing, the fourth technique
that is discussed below, to find out more about
dark energy.

The cosmic microwave background also provides a
"backlight" to detect clusters of galaxies through their
"shadows" as microwave photons scatter off the hot
electrons in the cluster core. Known as the Sunyaev–Zel'dovich effect, several research groups hope to use
this to measure the size of clusters and hence their distances
in order to investigate dark energy. Experiments
such as ACT and APEX-SZ in Chile and at the
South Pole Telescope are just becoming operational
to try this approach.

Supernovae revisited

The most direct way to measure cosmic expansion is the
same technique that was used to discover dark energy
in the first place: observations of distant "Type Ia"
supernovae. Remarkably, all measurements of these
exploding stars show that they have the same standardized
brightness no matter whether they occurred yesterday
or 10 billion years ago (their intrinsic brightness
may vary, but once the time it takes for their light to
peak and fade is taken into account, their brightness
appears quite standard). As such, the measured brightness
of supernovae — which can be seen right out to the
depths of the universe — tell us how far away they are
(see "Studying supernovae", below).

The discovery of the accelerating universe 10 years
ago was based on observations of a few dozen supernovae,
but since then researchers have measured several
hundred and obtained a rough picture of the last
10 billion years of cosmic expansion. Further progress
in supernova cosmology requires even more accurate
and detailed measurements over this full time period.
This is similar to the way one might build a picture of
the Earth's climatic history by studying tree rings, with
wide rings pointing toward a warmer year. To obtain
the clearest picture of the climate, one does not only
want to examine more trees but to gather enough data
from different types of tree in different environments
to create a more accurate understanding.

For the immediate future, surveys such as the ongoing
Nearby Supernova Factory will study supernovae
from just the most recent 1 billion years in exquisite
detail, while PanStarrs starting in 2008 in Hawaii and
the Dark Energy Survey in 2010 in Chile will probe
about 7 billion years back in time, although in less detail.
However, it will be difficult to distinguish between
various models for dark energy until an experiment
combines the best qualities of each type of survey:
in other words, a highly detailed examination of individual
supernovae over the entire period that dark
energy has been influencing the universe. For distant
sources, light is redshifted to near-infrared wavelengths,
so this goal requires a space-based observatory.

In 1999 the Supernova/Acceleration Probe (SNAP)
was proposed to deliver a detailed "tree by tree" comparison
for some thousands of supernovae spanning
the last 10 billion years. NASA and the US Department
of Energy have since agreed to carry out a Joint Dark
Energy Mission, and there are now at least two additional
proposals. These include the Dark Energy Space
Telescope (Destiny), which would study supernovae
and weak lensing, and the Advanced Dark Energy
Physics Telescope (ADEPT), which would study baryon acoustic oscillations and supernovae. Both are
vying with SNAP for funding, and the successful mission
will take off in 2014 at the earliest (see Physics
World October p8, print edition only).

The final weapon we have to tackle dark energy is
weak gravitational lensing, which involves measuring
patterns in the distortion of light emitted by distant
galaxies due to the gravitational fields of intervening
mass concentrations such as galaxies. Imagine someone
holding a lens between you and a wall covered with
patterned wallpaper; the distortion will depend on both
the strength of the lens and how far it is from both your
eyes and the wall. Weak lensing therefore probes dark
energy both directly via the stretching of distances and
indirectly via the mass of galaxy clusters, since the faster
the expansion the harder it is for gravity to pull mass
together. When taken together, the largest and deepest
surveys undertaken so far image about 1/400 of the
whole sky, mostly from data taken by the Canada–France–Hawaii Telescope Legacy Survey.

Surveys some ten times larger, to various depths, will
be carried out over the next few years by the Kilodegree
Survey in Chile, PanStarrs and the Dark Energy Survey.
A new ground-based Large Synoptic Survey Telescope
(LSST), starting in 2013 or later, is also planned to survey
half of the entire sky, while the SNAP mission also
includes a space-based weak-lensing survey that can
cover 1/10 of the sky deeply and with high resolution.

Such data, especially when combined with a pure distance
probe such as supernova surveys, should be able
to provide precise tests of dark-energy properties —
including shedding light on the key question of whether
dark energy is a new ingredient of the universe or a
manifestation of new laws of gravity. This is because the
warping of light imaged by weak gravitational lensing
is affected by both the acceleration of the universe and
the strength of gravity, while supernova distances only
depend on the acceleration of the universe — regardless
of whether it is driven by new gravity or a new quantum
field. Only by using both a distance probe like supernovae
and a growth probe like weak lensing can we
separate these effects and discover the real physical origin
of our immensely puzzling, accelerating universe.

A bright future for dark energy

In the next 10 years we can be optimistic about advances
in our understanding of dark energy. The
sophisticated next-generation experiments being designed
will greatly improve the accuracy of dark-energy
measurements using a range of techniques, many of
which complement one another and therefore take us
closer to understanding the properties of dark energy.
In 10 years' time we should be able to determine the
equation of state to a precision of 2% and see if it varied
by more than 10% over the last 10 billion years, while
also testing whether the new physics involves a new
quantum field or a new theory of gravity (see "Constraining dark energy").

With such advances we should be able to move firmly
into the stage of accepting the new physics of our accelerating
universe. Perhaps we will even appreciate that
the puzzles of why dark energy exists and why it exists
now have simple solutions that reveal something beautiful
about the underlying physics. But we should also
not forget that the field of dark energy is very young,
and that we may have a long and exciting period of
exploration ahead before it matures.

Understanding the equation of state for dark energy
could also dramatically alter our knowledge of the fate
of the universe. For example, continued acceleration
would lead to an ever less-dense and colder universe,
with the horizon of the visible universe closing in
around each observer and ultimately leaving us in a
truly dark universe. But a better understanding of dark
energy could raise other profound questions, too.

If the accelerated expansion is indeed a window on
new theories of gravity, for instance, could it reveal
hidden dimensions of space–time? Is dark energy completely
dark, uncoupled to matter and other quantum
fields? Can the clumping of dark energy — a necessary
adjunct to any variation of dark energy over time — be
detected? Do its spatial perturbations travel at the
speed of light, as for the simplest scalar-field explanations,
or perhaps slower or even faster than light? And
is there a related variation in what we thought were
fundamental constants, such as Newton's gravitational
constant or the mass of the electron?

The pursuit of answers to the outstanding questions
about the nature of our universe requires theory, simulation
and observations to go hand in hand. In the
quest for dark energy we will unavoidably and delightedly
gather data on and develop understanding of
the more familiar astrophysical universe too: stars,
galaxies, clusters, cosmic radiation backgrounds, neutrinos
and discoveries not yet imagined. The way forward
is challenging. But cosmologists have clear ideas
for implementing advanced probes to continue the remarkable
progress in the physics revolution of the
accelerating universe.

Studying supernovae

By measuring the universe's expansion using exploding stars — supernovae — as
distance markers, scientists hope to answer some of the most fundamental
questions of existence, such as whether the universe is infinite, whether it is going to
continue to expand forever, or whether gravity will slow the expansion so much that
the universe will eventually begin to contract and ultimately end in a "big crunch".
Supernovae are useful in this regard because they are so bright that they can be seen
here on Earth even if their light has been travelling for 10 billion years before it
reaches us. Moreover, there is a certain class of supernovae — known as Type Ia — all
of which brighten to the same peak value before beginning to fade. Since we know
the speed of light, we can calculate how long ago these explosions occurred simply
by measuring the apparent peak brightness of the supernovae today.

What scientists need though are supernovae with a variety of apparent
brightnesses, in other words, those that are at a range of different distances from
Earth. Supernovae emit mostly short-wavelength blue light that is stretched to longer,
redder wavelengths as the universe expands. By measuring the size of this "redshift",
one can determine the size of the universe when the explosion occurred relative to its
size today. Although the astronomers Walter Baade and Fritz Zwicky had already
suggested in the 1930s that such a measurement could be made, supernovae at any
given redshift have a variety of actual brightnesses, which meant that the idea
languished till the mid-1980s when the more homogeneous Type Ia supernovae were
recognized. Advances in computing and camera technology also helped revitalize
this approach: the latest cameras were not only much more sensitive than
photographic plates, but were also digital, which meant that their images could be
easily analysed by computer. In particular, one could search for supernovae by
scanning through many galaxies in one night.

Even so, it was not clear in the late 1980s that very distant supernovae could be
found and studied by carrying out supernova searches. Indeed, a team of
astronomers in Denmark, led by Hans Nørgaard-Nielsen, had already carried out a
huge supernova search between 1986 and 1988 that had yielded just one distant
Type Ia supernova; worse still, it had already faded well past its peak brightness.

A decade more of effort was needed to crack the case (see "Critical Point: Dark energy"), including new techniques to find and study entire
batches of distant Type Ia supernovae before they reached their peak brightness. In
presentations at scientific conferences at the start of 1998 and through papers
submitted later that year, two teams — the High-Z Supernova Search team led by
Brian Schmidt from the Australian National University and the Supernova Cosmology
Project led by one of the present authors (SP) — presented startling results. Although
they had been trying to measure the extent to which the cosmic expansion was
slowing down, both teams had found signs that the expansion was speeding up. To
see a supernova that had been redshifted by a particular amount, both teams found
it was necessary to look at fainter and more distant supernovae than expected. In
other words, the universe must be expanding faster now than in the past.

Now, a decade later, scientists still have no idea why the universe's expansion is
accelerating. Perhaps it is a sign that Einstein's general theory of relativity will have to
be revised. But if the acceleration is due to so-called dark energy, then we are left with
an equally difficult problem — namely that almost three-quarters of the stuff in the
universe is made from something we know nothing about.

At a Glance: Dark energy

Discovered 10 years ago from observations of supernovae made by
two independent international teams, the cosmic acceleration is one of the most
profound discoveries in cosmology

The driving force behind cosmic acceleration is often attributed to "dark energy" —
an unknown substance that is gravitationally repulsive and makes up a staggering
75% of the mass–energy content of the universe

Current data suggest that dark energy could be some kind of "cosmological
constant", which was first proposed by Einstein in 1917 and which has a
quantum-mechanical interpretation as vacuum energy

The key question facing researchers today is whether dark energy is indeed a
cosmological constant or something else more exotic. Resolving this involves
measuring the equation of state parameter, w, much more precisely

More accurate measurements of supernovae, baryonic acoustic oscillations, the
cosmic microwave background and weak gravitational lensing should help answer
this question in the next decade

Dark energy could ultimately leave our universe in total darkness by causing
objects to recede from the Earth ever more quickly until they fade from view

About the author

9 comments

First, before looking forward to the decade ahead, one would do well to see what else have taken place in this very field to date. In that regard, please be good enough to access (1) where an Editorial Summary from Nature is also highlighted. It followed a breakthrough discovery last year that brought into question, to say the least, the ‘standard candles’ used here that led to this "mystery of the accelerating universe." Thank you.(1) www.sittampalam.net/Editors.htm

DARK MATTER = ACCELLERATING UNIVERSE

VERY THOROUGH ARTICLE - COVERS THE PROBLEM AND DOESN'T STINT ON REVEALING WHAT IS NOT KNOWN ABOUT THE UNIVERSE (MOST AUTHORS TRY TO COVER UP THE HARD FACT THAT THE ACCELERATING UNIVERSE MEANS THAT SCIENCE IS, AT PRESENT, STUPID!

Dark matter is easy.

Anyway, why do redshifts merely mean these deep-field bodies are in recession? As their measurements go farther back in time, they represent a smaller and thus heftier univers. Thus relativistic velocity is commensurate with gravital potential. One should express the Hubble constant in terms of energy also: [H] = km/s/Mpc -> [.5H^2] = J/kg·Mpc^2. As all sustems when were smaller, the same chunk of room would need to be projected in the deep background over the same sfairic breadth; farther objects must look bigger in the sky to fill up the background. When these objects are bigger in all directions, their head-on waves would manifest longer and be interpreted as a'waydrifting.

"Dark" matter thas at one time made liht energy, such as the microwave background, is /clear/ matter. Dark matter thas makes dark energy—that is, negative—is true dark matter. The latter splitd the vacuum intom positive and negative massly fases, where the positive clumps went intom another brane which is gravitally shielded from our brane, over our univers's inflationary eld after the big bang. Dark matter also undergoes low-energy nuclear reactions at the microwave band, which is why our late'est five billion years are contragravital again. Negative dark matter clumps at tweenclusterly voids, whereas positive clear matter clumps at supergalactic clusters.

How to control gravity:Take a glueball; take a bunch of neutrinos; stuff one intom the other. Bake them in a nuclear fire lest they shrivel in a puff. What you'll get is a mote of clear matter, A\0. A whit of gravital excitations from such shall be cleppen υ\0, the gravitòn. (As we hav the static, dunamic, and hreic fotòns γ/0, γ/1, and γ/2, we also hav the static, dunamic, and hreic gravitòns υ/0, υ/1, and υ/2.) Put the mote A\0 near a heavily-chargede nucleus such as lead or uranium, and it'll overfinely splittan intom positive and negative fases; the exòtic negative material fasis X\0 will conten motes of both elèctric charges. Under negative mass, anlik charges toclump and unlik charges tosund. These charges will grab normal, leihter unlik charges and heavier anlik charges to make hubrid exòtic atoms, along with a wild, noisy signature. For exempl, baruòns Ω−\− and Ω−\++ will make nuclei of indefinite size and weiht; with elèctròns, they make a gray goo which one may hold in a tank. Althouh such matter is contragravital, there isn't enouh to flip Earth's field intom repulsion; however, a craft with a good deal to lessen its overall weiht tom a few kilograms will be buoyant enouh for the atmòsfair to spit out. Stayun on the ground will mean the craft needs ballast as well, such as iron dust or watter; however, otherwise, the craft should hav neutral buoyansey with the loft. Normal propulsion will scootan the craft at explosive speeds and jolts; it would be easy for im to reach rocket-exhaust speeds, make right-ankle throws, etc.

By Aether Wave Theory (AWT)...

...the gravity is related to Universe expansion and the inertia is result of space-time R-1/R ("Klein bottle") transform, which manifests itself as an acceleration of the expansion, i.e. the so-called "dark energy". Both general relativity (GR), both quantum mechanics (QM) are approximate theories by dual way: while the quantum mechanics predicts the gradual dissolving of particle wave packets into vacuum, the GR predicts, all particles should collapse into singularities.

The AWT is based on the concept of hypothetical inertial environment of infinite mass/energy density (i.e. the Aether) and it's facing these conceptual problems by the assumption, the current Universe generation is formed by interior of giant collapsar, similar to black hole, which is collapsing with the increasing speed by the same way, like common stars. This collapse is perceived as an Universe expansion from internal perspective of observer, formed by standing wave packets (i.e. the particles) of nested E8 foam, forming the interior of Universe. For further discussion of this concept please visit the sciforums.com…showthread.php

Dark Energy

My initial reaction to the discovery that the Universal expansion appears to be accelerating was: WOW Einstein was even right when he thought that he was wrong! However, the 120 orders of magnitude discrepancy between vacuum energy and the cosmological constant soon convinced me that Lambda was too simple of an answer the apparent acceleration. Perhaps the problem is in our insistence in invoking a model of the universe that is too simple: perhaps the universe is not isotropic and homogeneous as is suggested by Mustapha Ishak, et. al. in:"Dark Energy or Apparent Acceleration Due to a Relativistic Cosmological Model More Complex than FLRW?" (arXiv:0708.2943v1 [astro-ph] 22 Aug 2007)

They conclude that "this preliminary work shows that the Szekeres inhomogeneous models provide a surprisingly good fit to the supernova data and supports apparent acceleration, and further investigations are required in order to fully explore this possibility".

David L. Wiltshire also invokes a complex distribution of matter in the universe in:

AbstractA new model of the observed universe, using solutions to the full Einstein equations, is developed from the hypothesis that our observable universe is an underdense bubble, with an internally inhomogeneous fractal bubble distribution of bound matter systems, in a spatially flat bulk universe. It is argued on the basis of primordial inflation and resulting structure formation, that the clocks of the isotropic observers in average galaxies coincide with clocks defined by the true surfaces of matter homogeneity of the bulk universe, rather than the comoving clocks at average spatial positions in the underdense bubble geometry, which are in voids...."

And he concludes "As a model cosmology, the present Fractal Bubble Universe is remarkable in that its gross features depend only on two already observed parameters, and the results obtained thus far are reasonably promising. If correct, then all observed quantities in cosmology must be systematically reanalysed. The determination of some quantities will require further development of our understanding of the inhomogeneous matter distribution within S, including the largest scale local voids (Tomita 2001), in particular. However, the present model offers a clear framework for calculations, as is demonstrated in Ref. I, where further steps are taken in the reanalysis of the hot Big Bang and observational implications for the CMBR. It would be ironic that Einstein’s idea concerning the irrelevance of the cosmological constant, and his idea of the importance of Mach’s principle, may prove to both be right in understanding the universe."

We may need to reconsider our ‘dark energy’ paradigm and begin to accept that our universe is not as simply constructed as we wish it were. We may be in a position analogous to that of the physicist who was asked to help is dairy farmer friend to increase the milk yield of his herd. The physicist began: “We will first consider the case of a spherical, homogeneous and isotropic cow …”

Expansion of the radiation explains accelaration

Ten years after astrophysicists discovered that the expansion of the universe is accelerating, further measurements have given us few clues into the nature of the dark energy that drives it.

It is not the universe that is expanding -- it is the radiation that is forced forward by the entropy-effect that causes the radiation to move from higher to lower energy toward equilibrium in the lowest CBR-temperature.

Both Planck and Hubble found that phenomenon -- but both misinterpreted it.Planck misinterpreted the measurements of the fractional displacement the waveunits from the heat-radiation's wavespectrum as quantum-jump.Hubble misinterpreted the he same displacement as Doppler-velocity that was the only known explanation.

I have discovered the natural law that explains how the wave-energy is propagating (and accelerating) in hydrodynamics, electrodynamics (light), and air-dynamics (sound).

So there is no need for dark energy-hypothesis.Neither any hypothesis like dark matter is needed to explain the flat galaxy-curve velocity, because the explanation is that "they" have just mixed up angular velocity with orbital velocity.

Dark energy does not fit Big Bang Cosomology

I developed a new Hubble formula (Dan Visser). This formula emerged from my detailed "dark energy-dark matter theory". In this theory Hubble-expansion-speed is replaced by recalculation of space and time by torus-fractals. In my new cosmological model dark energy and dark matter are matching a torus as two expressions of the same phenomenon. At the base of my theory lies a conceptualization of a thought-experiment with hawking-radiation of a small and big black hole, which turns into a dark energy force-information-formula for a recalculated universe. This approach seems new and opens up a completely different view on physics and consciousness. In a follow-up I formulized my theory into holografic torus-fractals to be buildingstones in an underlaying level of quantum-dynamics. I combined this with c.H, which is the anomaly for several satelites which decelerate. In my theory this is caused by dark matter (I refer to recent research by John Anderson). This provided to me a formula to replace the Hubble-constant. My (new) "recalculation-universe-formula" turns out to be a product of an elementary spin (h), a spin for dark matter and a two spins for dark energy. The impact of my research concludes the Big Bang universe is a suggestive dynamics. This means we observe an accelerating expansion, while instead it is an expanding torus. We are located in just a small part of this torus.I refer to my website for more infomation: www.darkfieldnavigator.comKind regards,Dan Visser